Introduce a new helper function to decode x86 instructions from a
raw instruction byte stream. MSHV delivers an instruction stream in a
buffer of the vm_exit message. It can be used to speed up MMIO
emulation, since instructions do not have to be fetched and translated.
Signed-off-by: Magnus Kulke <magnusku...@linux.microsoft.com>
---
target/i386/emulate/x86_decode.c | 32 +++++++++++++++++++++++++++-----
target/i386/emulate/x86_decode.h | 11 +++++++++++
target/i386/emulate/x86_emu.c | 3 ++-
target/i386/emulate/x86_emu.h | 1 +
4 files changed, 41 insertions(+), 6 deletions(-)
diff --git a/target/i386/emulate/x86_decode.c b/target/i386/emulate/x86_decode.c
index 88be9479a8..7a862b976e 100644
--- a/target/i386/emulate/x86_decode.c
+++ b/target/i386/emulate/x86_decode.c
@@ -60,6 +60,7 @@ static inline uint64_t decode_bytes(CPUX86State *env, struct
x86_decode *decode,
int size)
{
uint64_t val = 0;
+ target_ulong va;
switch (size) {
case 1:
@@ -71,10 +72,16 @@ static inline uint64_t decode_bytes(CPUX86State *env,
struct x86_decode *decode,
VM_PANIC_EX("%s invalid size %d\n", __func__, size);
break;
}
- target_ulong va = linear_rip(env_cpu(env), env->eip) + decode->len;
- emul_ops->read_mem(env_cpu(env), &val, va, size);
+
+ /* copy the bytes from the instruction stream, if available */
+ if (decode->stream && decode->len + size <= decode->stream->len) {
+ memcpy(&val, decode->stream->bytes + decode->len, size);
+ } else {
+ va = linear_rip(env_cpu(env), env->eip) + decode->len;
+ emul_ops->fetch_instruction(env_cpu(env), &val, va, size);
+ }
decode->len += size;
-
+
return val;
}
@@ -2076,9 +2083,8 @@ static void decode_opcodes(CPUX86State *env, struct
x86_decode *decode)
}
}
-uint32_t decode_instruction(CPUX86State *env, struct x86_decode *decode)
+static uint32_t decode_opcode(CPUX86State *env, struct x86_decode *decode)
{
- memset(decode, 0, sizeof(*decode));
decode_prefix(env, decode);
set_addressing_size(env, decode);
set_operand_size(env, decode);
@@ -2088,6 +2094,22 @@ uint32_t decode_instruction(CPUX86State *env, struct
x86_decode *decode)
return decode->len;
}
+uint32_t decode_instruction(CPUX86State *env, struct x86_decode *decode)
+{
+ memset(decode, 0, sizeof(*decode));
+ return decode_opcode(env, decode);
+}
+
+uint32_t decode_instruction_stream(CPUX86State *env, struct x86_decode *decode,
+ struct x86_insn_stream *stream)
+{
+ memset(decode, 0, sizeof(*decode));
+ if (stream != NULL) {
+ decode->stream = stream;
+ }
+ return decode_opcode(env, decode);
+}
+
void init_decoder(void)
{
int i;
diff --git a/target/i386/emulate/x86_decode.h b/target/i386/emulate/x86_decode.h
index 87cc728598..9bc7d6cc49 100644
--- a/target/i386/emulate/x86_decode.h
+++ b/target/i386/emulate/x86_decode.h
@@ -269,6 +269,11 @@ typedef struct x86_decode_op {
target_ulong ptr;
} x86_decode_op;
+typedef struct x86_insn_stream {
+ const uint8_t *bytes;
+ size_t len;
+} x86_insn_stream;
+
typedef struct x86_decode {
int len;
uint8_t opcode[4];
@@ -295,12 +300,18 @@ typedef struct x86_decode {
struct x86_modrm modrm;
struct x86_decode_op op[4];
bool is_fpu;
+
+ x86_insn_stream *stream;
} x86_decode;
uint64_t sign(uint64_t val, int size);
uint32_t decode_instruction(CPUX86State *env, struct x86_decode *decode);
+uint32_t decode_instruction_stream(CPUX86State *env,
+ struct
x86_decode *decode,
+ struct x86_insn_stream *stream);
+
target_ulong get_reg_ref(CPUX86State *env, int reg, int rex_present,
int is_extended, int size);
target_ulong get_reg_val(CPUX86State *env, int reg, int rex_present,
diff --git a/target/i386/emulate/x86_emu.c b/target/i386/emulate/x86_emu.c
index 7773b51b95..73c9eb41d1 100644
--- a/target/i386/emulate/x86_emu.c
+++ b/target/i386/emulate/x86_emu.c
@@ -1241,7 +1241,8 @@ static void init_cmd_handler(void)
bool exec_instruction(CPUX86State *env, struct x86_decode *ins)
{
if (!_cmd_handler[ins->cmd].handler) {
- printf("Unimplemented handler (" TARGET_FMT_lx ") for %d (%x %x) \n",
env->eip,
+ printf("Unimplemented handler (" TARGET_FMT_lx ") for %d (%x %x) \n",
+ env->eip,
ins->cmd, ins->opcode[0],
ins->opcode_len > 1 ? ins->opcode[1] : 0);
env->eip += ins->len;
diff --git a/target/i386/emulate/x86_emu.h b/target/i386/emulate/x86_emu.h
index 555b567e2c..761e83fd6b 100644
--- a/target/i386/emulate/x86_emu.h
+++ b/target/i386/emulate/x86_emu.h
@@ -24,6 +24,7 @@
#include "cpu.h"
struct x86_emul_ops {
+ void (*fetch_instruction)(CPUState *cpu, void *data, target_ulong addr,
int bytes);
void (*read_mem)(CPUState *cpu, void *data, target_ulong addr, int bytes);
void (*write_mem)(CPUState *cpu, void *data, target_ulong addr, int bytes);
void (*read_segment_descriptor)(CPUState *cpu, struct
x86_segment_descriptor *desc,
--
2.34.1
